The most persistent and intractable cause of infant and child morbidity in the U.S. remains preterm and low birthweight deliveries. Despite many efforts at increasing prenatal care, rates of preterm low birthweight delivery have not substantially changed in the last decade. Even more disturbing is the observation that immigrant Hispanic women experience worsening birth outcomes the longer they live in the U.S., despite increasing access to prenatal care, improved socio-economic status and better education. This study will examine the effects of acculturation and occupation on preterm low birthweight (PTLBW) among Hispanic women. Studies show that recent Hispanic immigants have better birth outcomes than long-term immigrants or their US-born counterparts. Based on a review of the literature, the investigators hypothesize that farm labor and/or pesticide exposure can best explain the increased rate of PTLBW among Hispanic women. The researchers will also test other changes associated with acculturation to US society, such as dietary changes, and increased genital infections due to greater sexual exposures, and their effects on preterm low birthweight births. To test these hypotheses, the researchers will: 1) Conduct a prospective cohort study of PTLBW on approximately 1,500 Hispanic women obtaining prenatal care through the OB/GYN group associated with San Joaquin General Hopital in Stockton, CA and identify risk factors that change with acculturation to the U.S.; 2) Ascertain pregnancy outcome from medical records and participant follow-up; 3) Analyze the association of potential risk factors for which data are collected to identify factors significantly associated with both acculturation and PTLBW. This study will enroll women at first prenatal care visit through the San Joaquin General Hospital OB/GYN group in Stockton, CA. The researchers will interview women for occupational risks, nutritional status, and pregnancy risks; screen for Bacterial Vaginosis, Chlamydia and Gonorrhea; and test urine for assays of pesticide metabolities. Outcome data on birthweight and gestational age at delivery will be collected from medical records after delivery. Data analysis will examine the relationship between occupational risks, pesticide exposures, other risk factors and acculturation, and their effects on birthweight and gestational age at delivery.